For the supply of cooling lubricant in connection with rotating spindles, so-called rotary feed inlets are used, which make it possible to introduce a coolant into the quickly rotating spindle shaft, guide the coolant axially through the spindle shaft, and lead-out the coolant at the other spindle end, for example on a tool or a workpiece. At the present time, slide bearing rings of ceramic or ceramic seal disks are used for the sealing of these coolant supplies. These ceramic seal disks are subject to relatively strong wear during operation, are very expensive, and can suddenly fail without advance warning. Upon failure of such seals, the cooling liquid penetrates into the spindle motor, which can lead to a total loss of the spindle.
Such rotary feed inlets for the supply of cooling lubricant in connection with rotating spindles with ceramic seal disks are, for example, sufficiently known from the JP 09196265 A or the DE 10349968 A1.
Although a main seal for spindle shafts is known from the WO 03/081095 A1, which is embodied as a brush seal, nonetheless this serves only as a simple seal against the leaking-out of lubricant and the penetration of dirt particles. A functioning seal for a rotary feed inlet is not set forth therein.